Chest dual-energy CT to assess the effects of steroids on lung
function in severe COVID-19 patients
by Gaetano
Perchiazzi, Aleksandra Larina, Tomas Hansen, Robert Frithiof, Michael
Hultström, Miklos Lipcsey and Mariangela Pellegrini
Critical Care volume 26,
Article number: 328 (2022)
Background
Steroids have been shown to reduce inflammation, hypoxic
pulmonary vasoconstriction (HPV) and lung edema. Based on evidence from
clinical trials, steroids are widely used in severe COVID-19. However, the
effects of steroids on pulmonary gas volume and blood volume in this group of
patients are unexplored.
Objective
Profiting by dual-energy computed tomography (DECT), we
investigated the relationship between the use of steroids in COVID-19 and
distribution of blood volume as an index of impaired HPV. We also investigated
whether the use of steroids influences lung weight, as index of lung edema, and
how it affects gas distribution.
Methods
Severe COVID-19 patients included in a single-center
prospective observational study at the intensive care unit at Uppsala
University Hospital who had undergone DECT were enrolled in the current study.
Patients’ cohort was divided into two groups depending on the administration of
steroids. From each patient’s DECT, 20 gas volume maps and the corresponding 20
blood volume maps, evenly distributed along the cranial–caudal axis, were
analyzed. As a proxy for HPV, pulmonary blood volume distribution was analyzed in
both the whole lung and the hypoinflated areas. Total lung weight, index of
lung edema, was estimated.
Results
Sixty patients were analyzed, whereof 43 received steroids.
Patients not exposed to steroids showed a more extensive non-perfused area (19%
vs 13%, p < 0.01) and less homogeneous pulmonary blood volume of
hypoinflated areas (kurtosis: 1.91 vs 2.69, p < 0.01), suggesting a
preserved HPV compared to patients treated with steroids. Moreover, patients
exposed to steroids showed a significantly lower lung weight (953 gr vs 1140
gr, p = 0.01). A reduction in alveolar–arterial difference of oxygen
followed the treatment with steroids (322 ± 106 mmHg at admission vs
267 ± 99 mmHg at DECT, p = 0.04).
Conclusions
The use of steroids might cause impaired HPV and might
reduce lung edema in severe COVID-19. This is consistent with previous findings
in other diseases. Moreover, a reduced lung weight, as index of decreased lung
edema, and a more homogeneous distribution of gas within the lung were shown in
patients treated with steroids.
